The present disclosure relates to the subject matter contained in Japanese Utility Model Application No. 2002-000445 filed Feb. 4, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a video projector for projecting a video image onto a screen.
2. Description of the Related Art
Conventionally, a video projector is used for various purposes such as in-house meeting and seminar presentation. Usually, the video projector is placed on a desk or table, and adjusters are provided in front, rear, right and left sides of a bottom surface of a cabinet body of the video projector in order to adjust up-down or left-right inclination of a video image projected onto a screen (e.g. Japanese Patent Laid-Open No. 5883/1997, Japanese Utility Model Laid-Open No. 26382/1994, Japanese Patent Laid-Open No. 2001-5094).
Generally, the video projector has a light reflecting mirror device driven on the basis of a bit digital video signal, and a projection lens through which light reflected by the light reflecting mirror device is projected. In most cases, the projection lens is disposed in a front surface of the cabinet body so as to be located eccentrically on either right or left side of the front surface because both increase in optical path length in the cabinet of the projector and reduction in size of the cabinet are required.
In the configuration of the video projector described above, the adjusters are provided only in the bottom surface of the cabinet body, so that there is no degree of freedom in placement of the video projector such as horizontal placement or vertical placement. Particularly, when the video projector must be placed on a table having a narrow space or when the video projector can be placed on only a half of a table, it is difficult to adjust and set the video projector properly.
The invention is developed for solving the problem and an object of the invention is to provide a video projector having degree of freedom in placement of the video projector such as horizontal placement or vertical placement to facilitate placement and/or adjustment of the video projector for projection of a video image onto a screen.
In order to achieve the foregoing object, according to a first aspect of the invention, there is provided a video projector having: a light source; a light reflecting mirror device for reflecting light emitted from the light source; a light reflecting mirror device drive circuit for driving the light reflecting mirror device on the basis of a bit digital video signal; a cabinet which is shaped like a flat and substantially rectangular cube, and in which the light source, the light reflecting mirror device and the light reflecting mirror device drive circuit are disposed, the cabinet having front, bottom, top, left side and right side surfaces; a projection lens which is provided in the front surface of the cabinet so as to be located eccentrically on either of left or right side of the front surface and by which a video image of reflected light formed by the light reflecting mirror device is enlarged and projected onto a screen; adjusters provided in the bottom and top surfaces of the cabinet and located on left and right sides of the bottom and top surfaces close to the front surface of the cabinet for adjusting inclination and/or height of the projector when the projector is placed on a table, the adjusters being supported by shafts perpendicular to the front surface so as to be rotatable in an angular range of at least 90xc2x0, the adjusters being configured so that postures of the adjusters are retained in accordance with placement of the cabinet in such a manner that the cabinet is placed horizontally when the adjusters are postured to be perpendicular to the bottom and top surfaces of the cabinet and the cabinet is placed vertically when the adjusters are postured to be perpendicular to the left and right side surfaces of the cabinet; and a horizontal/vertical placement change-over switch for supplying a signal to the light reflecting mirror device drive circuit in accordance with the placement of the projector in such a manner that the signal is generated as a signal for rotating a video image formed on the basis of the bit digital video signal left or right by 90xc2x0 when horizontal placement of the cabinet needs to be changed over to vertical placement, and that the signal is generated as a signal for turning the video image upside down when the cabinet placed horizontally needs to be turned upside down.
In the configuration, the cabinet is placed horizontally when the adjusters are postured to be perpendicular to the bottom surface of the cabinet, but the cabinet is placed vertically when the adjusters are postured to be perpendicular to the right and left side surfaces of the cabinet. In addition, when the cabinet is placed horizontally, the placement mode of the cabinet can be selected from a normal mode in which the bottom surface of the cabinet faces downward and a reverse mode in which the top surface of the cabinet faces downward, that is, the cabinet is turned upside down. In accordance with the mode selection, the projection lens can be located eccentrically on either of the left and right sides of the cabinet when viewed from the front of the cabinet. In addition, when the cabinet is placed vertically, the placement mode of the cabinet can be selected from a mode in which the left side surface of the cabinet faces downward and a mode in which the right side surface of the cabinet faces downward. In addition, when the cabinet is placed horizontally or vertically, the horizontal/vertical placement change-over switch can be operated as follows. When the cabinet placed horizontally needs to be placed vertically, the horizontal/vertical placement change-over switch can be operated so that a video image formed on the basis of the bit digital video signal at the time of the horizontal placement of the cabinet is rotated left or right by 90xc2x0 to achieve the vertical placement of the cabinet. On the other hand, in the case where the projector needs to be turned upside down when the cabinet is placed horizontally, the horizontal/vertical placement change-over switch can be operated so that a video image is turned upside down. In this manner, the video image projected onto the screen is always provided as a normally erecting image.
According to a second aspect of the invention, there is provided a video projector having: a cabinet shaped like a flat and substantially rectangular cube, the cabinet having front, bottom, top, left side and right side surfaces; a projection lens which is provided in the front surface of the cabinet so as to be located eccentrically on either of left or right side of the front surface and by which a video image is enlarged and projected; and adjusters provided in the bottom and top surfaces of the cabinet and located on right and left sides of the bottom and top surfaces close to the front surface of the cabinet for adjusting inclination and/or height of the projector when the projector is placed on a table, the adjusters being supported rotatably by shafts perpendicular to the front surface, wherein the cabinet can be placed freely regardless of whether it is placed horizontally or vertically, in such a manner that the cabinet is placed horizontally when the adjusters are postured to be perpendicular to the bottom and top surfaces of the cabinet and the cabinet is placed vertically when the adjusters are postured to be perpendicular to left and right side surfaces of the cabinet. In this configuration, the cabinet is placed horizontally when the adjusters are postured to be perpendicular to the bottom surface of the cabinet, but the cabinet is placed vertically when the adjusters are postured to be perpendicular to the left and right side surfaces of the cabinet. In this manner, the projector can be placed in any desirable posture, so that a video image can be projected onto the screen from any position.
According to a third aspect of the invention, there is provided a video projector defined in the second aspect of the invention and further having a horizontal/vertical placement change-over switch for performing change-over in accordance with horizontal/vertical placement of the cabinet to generate a signal for rotating a projected video image left or right by 90xc2x0 when horizontal placement of the cabinet is changed over to vertical placement. In this configuration, the video image can be projected onto a screen correctly regardless of whether the video projector (cabinet) is placed horizontally or vertically.